While scientists have predicted that the orientation of atoms along the edges of the lattice would affect the material's electronic properties, the prediction had not been proven experimentally.

Now, researchers at the University of Illinois (U. of I.) say they have proof.

"Our experimental results show, without a doubt, that the crystallographic orientation of the graphene edges significantly influences the electronic properties," said Joseph Lyding, a professor electrical and computer engineering at the U. of I.

"To utilize nanometer-size pieces of graphene in future nanoelectronics, atomically precise control of the geometry of these structures will be required," he added.

To carry out their work, the researchers developed a method for cutting and depositing nanometer-size bits of graphene on atomically clean semiconductor surfaces like silicon.

Then they used a scanning tunneling microscope to probe the electronic structure of the graphene with atomic-scale resolution.

"From this emerged a clear picture that edges with so-called zigzag orientation exhibited a strong edge state, whereas edges with armchair orientation did not," said Lyding.

"We found that pieces of graphene smaller than about 10 nanometers with predominately zigzag edges exhibited metallic behavior rather than the semi conducting behavior expected from size alone," he added.

"This has major implications in that semiconducting behavior is mandatory for transistor fabrication," he further added.

Unlike carbon nanotubes, graphene is a flat sheet, and therefore compatible with conventional fabrication processes used by today's chipmakers.

But, based on the researchers' experimental results, controlled engineering of the graphene edge structure will be required for obtaining uniform performance among graphene-based nanoelectronic devices.

"Even a tiny section of zigzag orientation on a 5-nanometer piece of graphene will change the material from a semiconductor into a metal," Lyding said. (ANI)